Ruthenium complexes and substituted polypyridines in photophysical and electron transfer studies

Sammanfattning: Organic molecules acting as electron acceptors and ligandsfor metal complexes were synthesized. N-alkylation of4,4'-bipyridine and nicotinamide yielded electron transport andacceptor molecules. By regioselective functionalization of2,2'-bipyridine (bpy), several novel ligand molecules wereobtained. The ligand molecules bind to Ru(II) in a bidentate ortridentate fashion, utilizing the nitrogen atoms and oxygenatoms of the ligands. Synthesis of three types of Ru(II)complexes were performed. Various methods of sequentialaddition of different ligands were used to obtain heterolepticcomplexes. The Ru(II) complexes were charactertized by NMR andEPR spectroscopy, X-ray crystallography, electrosprayionization mass spectrometry and optical spectroscopy(photophysical and photochemical properties). The photophysicalstudies were performed in the temperature range 343-77 K, andthe temperature dependence of the emission properties (lifetimeτ and quantum yield Φem) was investigated. The photoinduced electrontransfer properties were studied by time-resolved absorptionspectroscopy in solution and in microheterogeneous media(vesicles). As electron acceptors, various N-alkylated,viologen-type organic molecules were used. A novel model systemfor a photosynthetic reactions center, a binuclearsupramolecular complex containing Mn(II) and Ru(II) metal ionsdisplaying photoinduced intramolecular electron transfer wasdeveloped. Technological applications based on the results ofthis type of fundamental scientific research may come tocontribute to the development of future energy supplysystems.Keywords:ruthenium, photophysics, photocliemistry,spectroscopy, synthesis, bipyridine, ligand, homoleptic,heteroleptic, metal complex.